McCaskill has been a stalwart for transparency on the committee. Republicans Kelly Ayotte of New Hampshire, John McCain of Arizona and David Vitter of Louisiana have joined the opposition, but all three voted to conduct the markup proceedings behind closed doors in 2013.
The strongest support for transparency from lawmakers came in 2010 and 2011. In each of those years, nine senators voted to keep the doors to the full committee markup open, but they were still a minority.
Levin does not intend to respond to the Standing Committee’s most recent letter, according to spokeswoman Tara Andringa.
Rep. Elijah Cummings, D-Md., right, hugs Harold Schaitberger, General President of the International Association of Fire Fighters, after the Congressman spoke at the IAFF's Legislative Conference General Session at the Hyatt Regency on Capitol Hill, March 9, 2015. The day featured addresses by members of Congress and Vice President Joe Biden.